The present invention relates to the control of an internal combustion engine. More specifically, the present invention relates to an encoded crank system that may be integrated seamlessly with multiple internal combustion engines having a plurality of cylinder configurations.
Integration of vehicle parts, electronic components, and software into automotive vehicles is becoming increasingly important in today""s automotive industry. Traditional methods of vehicle assembly for vehicle parts and components are giving way to flexible modular design and manufacturing techniques.
Presently, automotive companies manufacture a wide range of internal combustion engine (ICE) configurations such as in-line four-cylinder engines, in-line five-cylinder engines, in-line six-cylinder engines, and V-six and eight engines. As is known in the art of four-cycle ICEs, position and timing information for a crankshaft and a camshaft is very important for the application and synchronization of spark and fuel. The faster the engine synchronization of spark and fuel, the smoother the engine start and the better the emission control.
Present ICEs are generally configured in an overhead valve (OHV) configuration where the valves are actuated via pushrods, or in an overhead cam configuration (OHC) where the valves are acted on directly by the camshaft. The camshaft is driven by the crankshaft through a 1:2 reduction (i.e., two rotations of the crankshaft equal one rotation of the camshaft), and the camshaft speed is one-half that of the crankshaft. The crankshaft and camshaft position, for engine control purposes, are measured at a small number of fixed points, and the number of such measurements may be determined by the number of cylinders in the ICE.
In today""s engine control systems, crankshaft speed is supplied by a crankshaft sensor to provide position, timing and/or speed information to an electronic controller for controlling the application of spark and fuel to the cylinders of an ICE. The crankshaft position sensor typically includes a variable reluctance or Hall effect sensor positioned to sense the passage of a tooth, tab and/or slot on a target or data wheel coupled to the crankshaft.
The target wheel or data wheel used in present crankshaft position systems generally includes a regular distribution of teeth, tabs and/or slots with substantially similar dimensions. In a four cycle ICE, the electronic controller must differentiate the intake, compression, power, and exhaust strokes since the cylinders will be at the top dead center (TDC) position during the compression and exhaust phases and at the bottom dead center (BDC) position during the intake and power phases. Accordingly, the application of fuel and spark in a typical ICE will not be applied until enough position information has been obtained from the crank or cam sensing systems. Thus, the engine controller must not only determine the TDC and BDC positions of the cylinder but also the state of the engine cycle to control fuel and spark.
Target or data wheels for a crankshaft that provide crankshaft position are traditionally designed to be specific for each engine configuration. These present systems have the disadvantages of requiring different hardware and software for each engine configuration. It would be advantageous for an automotive company to utilize a single type of generic crankshaft sensing system with a single generic target wheel and calibratible software that can be used on a plurality of engine configurations.
The present invention comprises a new crankshaft sensing system common to four cycle internal combustion engines (ICEs), including but not limited to three, four, five, six, eight, ten and twelve cylinder engines.
The crankshaft system, specifically the sensor and target wheel, provide an output signal with xe2x80x9ceventsxe2x80x9d at a fixed location relative to top dead center (TDC) compression for cylinders of the engine configurations listed above. This is achieved with the minimum number of sensing features possible to reduce the cost, complexity, and control system throughput of the crankshaft sensing system, while maximizing functionality and providing quick engine synchronization.
The present invention utilizes an encoded 58x target wheel having multi-dimensional teeth for engine timing functions that is compatible with existing control systems utilizing non-encoded 58x target wheels having uniform tooth dimensions. The term xe2x80x9c58xxe2x80x9d denotes that the target wheel includes 58 teeth and a synchronization area, and the term xe2x80x9cencodedxe2x80x9d denotes forming the teeth of a target wheel with irregular dimensions to generate a unique pulse train. For example, the pulse train will comprise a series of pulses having varying widths corresponding to time and tooth width on the target wheel. The benefits of the encoded 58x target wheel of the present invention include compatibility with engine control systems which utilize (the current 58x) non-encoded target wheels and the ability to synchronize the crankshaft within 36 degrees of rotation. The quicker the synchronization of the crank, the smoother the start of the engine with a concomitant reduction in emissions.
Another benefit of the invention is the quicker ability to recognize that synchronization of the engine has been lost in the case of noise affecting the crankshaft sensor. The quicker the recognition that synchronization has been lost, the quicker corrective action can be taken for subsystems that depend on a high degree of accuracy in crankshaft position.